As Much as 90% of the Matter in the Universe

As much as 90% of the matter in the universe may be unseen "dark matter." Where is this dark matter?

A) It seems to be rather uniformly distributed throughout the universe.
B) It is concentrated in the centers of galaxies,and may,in fact,be related to black holes at galactic centers.
C) It is concentrated in the planes of galaxies,but extends far beyond the visible galactic plane.
D) It appears to be concentrated in spherical haloes around galaxies,but extends several times the radius of visible matter.